The number of rooms is the count of whole rooms used for living purposes, such as living rooms, dining rooms, bedrooms, kitchens, finished attic or basement rooms, recreation rooms, lodgers rooms, and rooms used for offices by a person living in the unit. Not counted as rooms are bathrooms; halls, foyers, or vestibules; closets; alcoves; pantries; strip or pullman kitchens; laundry or furnace rooms; unfinished attics, basements, and other space used for storage.

In the computation of the median number of rooms, a continuous distribution was assumed, with the whole number of rooms as the midpoint of the class interval. For example, when the median was in the 3-room group, the lower and upper limits were assumed to be 2.5 and 3.5 rooms, respectively. The median was computed on the basis of the tabulation groups shown in the table. If the median falls in the category 8 rooms or more, it is shown in the table as 7.5+ rooms.